CN105430697A - Method and device for predicting channel switching time - Google Patents

Abstract

The invention discloses a method and a device for predicting channel switching time. The method comprises the following steps: receiving a service announcement frame and N time announcement frames sent by a server end; after receiving an instruction of a user for confirming invitation information, acquiring channel switching time point information of a receiving end in the i-th channel switching period; and predicting the channel switching time point information of the receiving end in the K-th channel switching period according to the channel switching cycle, channel switching delay time information, received channel switching time point information of the server end and the acquired channel switching time point information of the receiving end. Therefore, the method and the device provided by the embodiment of the invention have the advantage that channel switching time can be predicted accurately, so as to ensure consistency of channel switching time of the server end and the receiving end, effectively lower network resource consumption and indeterminacy caused by delay, and improve communication efficiency of data transmission.

Description

The method of predicted channel switching time and device

Technical field

The present invention relates to communication technical field, particularly the method for a kind of predicted channel switching time and device.

Background technology

Along with Global Auto recoverable amount significantly rising, traffic accidents takes place frequently and congestion in road problem grows with each passing day, therefore how automobile vendor, traffic control department, scientific research institutions, scientific & technical corporation all promote smooth traffic in the exploration of making great efforts, reduce the scheme of traffic accident.Inter-vehicle communication technology is technology day by day ripe in recent years, and it can pass through Dedicated Short Range Communications agreement, the running status between vehicle is accused it mutually, and predicts potential danger and the traffic of vehicle-surroundings with this.Therefore the communication success rate in car networking is crucial, and communication success rate has and has huge associating with the synchronousness between communication channel, so in the network of workshop, the synchronousness of communication channel is the most important thing.

There is the problem of channel allocation in current workshop network, in the U.S., Federal Communications Committee's frequency spectrum resource of 75Mhz that has been workshop network allocation, is divided into 7 channels, wherein 1 is CCH, control channel, for the security related information in mutual workshop, all the other 6 SCH, service channel, mutual periphery traffic information is set for car and basic traffic, therefore under the condition of injection frequency module, there is the situation that channel switches.Unite States Standard IEEE1609.4 specifies, every 50 milliseconds of switchings carrying out control channel, service channel, in order to ensure that the vehicle installing injection frequency module both can receive security classes message, also can receive peripheral path information simultaneously.But when channel switches, the switching time needing all nodes ensured in communication range is identical, otherwise can cause the dislocation of inter-nodal channel, has a strong impact on communication efficiency.

In correlation technique, in the network of workshop, the scheme of time synchronized mainly contains three classes, the Time Synchronization Mechanism based on sender, the Time Synchronization Mechanism based on sender, recipient and the Time Synchronization Mechanism based on recipient, recipient.Owing to needing experience network discovery phase and 2 stages of Network Synchronization based on the synchronization mechanism of sender, recipient, and each stage needs to carry out two-way data interaction, causes the resource occupation of bandwidth; Based on the Time Synchronization Mechanism of recipient, recipient owing to there is probabilistic block transmission delay, this scene that requires timing tracking accuracy high is switched to channel and inapplicable.But based on the Time Synchronization Mechanism of sender, datum mark is generally roadside unit, adopts the mechanism of broadcast, time synchronization information is passed to other node, reduce exchange message amount, save transmission bandwidth.

In correlation technique, the classic algorithm of the Time Synchronization Mechanism of sender is FTSP (FloodingTimeSynchronizationProtocol, inundation clock synchronization protocol), FTSP has root node only needs transmission broadcast, sending node just can make its neighbor node reach the feature of time synchronized by flooding mechanism, and this algorithm can carry out linear regression estimation to the problem of clock drift and clock skew.But, above-mentioned algorithm is also not suitable for being applied in the network of workshop, this is mainly because the limited bandwidth of workshop network, the feature that node accesses fast, leave, if use flooding mechanism to bring network storm, exhaust the characteristic of Internet resources, and calculate the Maintenance Table of root node and leaf node frequently, bring huge overhead.

At present, in the network of workshop, the synchronous method basic procedure that channel switches is as follows, and ISP initiates to invite to service recipients, if recipient is interested in the service on this channel, will perform the switching of this service channel.This general way only can meet the demand that channel switches in flow process, but in fact due to time uncertainty 20 to 30 milliseconds that the channel of receiving node switches, and the retention time of service channel and control channel is very short 50 milliseconds, therefore real available channel transfer rate only has about 50%, greatly reduces communication efficiency.

In sum, when in the network of workshop, channel switches, on the basis of time synchronized, how to add accurate predicted channel switching time is current urgent problem.

Summary of the invention

The present invention is intended to solve one of technical problem in correlation technique at least to a certain extent.

For this reason, one object of the present invention is to propose the method for a kind of predicted channel switching time, the method can accurate predicted channel switching time, thus switching time is consistent when ensure that the channel switching between service end with receiving terminal, effectively reduce the resource consumption of network and the uncertainty caused by delay, improve the communication efficiency of transfer of data.

Another object of the present invention is to propose the device of a kind of predicted channel switching time.

For achieving the above object, one aspect of the present invention embodiment proposes the method for a kind of predicted channel switching time, comprise the following steps: the service bulletin frame and the bulletin frame of N number of time that receive service end transmission, wherein, message request is comprised in described service bulletin frame, channel switch delay temporal information and the described service end channel switch time dot information at i-th channel switching cycle is comprised in i-th time bulletin frame, wherein, N is positive integer, and the time that cycle of being switched by channel of N and transmission described service bulletin frame consume determine, wherein, 1≤i≤N; After receiving user and confirming the confirmation instruction of described message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively; The cycle switched according to described channel, described channel switch delay temporal information, the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal predict the channel switch time dot information of described receiving terminal at K channel switching cycle, wherein, K is greater than N.

According to the method for predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received, then after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, finally according to the cycle that channel switches, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Therefore, the method can accurate predicted channel switching time, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

In addition, following additional technical characteristic can also be had according to the method for the present invention's above-mentioned predicted channel switching time:

In one embodiment of the invention, in the described cycle switched according to described channel, described channel switch delay temporal information, the received channel switch time dot information of described service end and the channel switch time dot information of accessed described receiving terminal predict that described receiving terminal is after the channel switch time dot information of K channel switching cycle, also comprise: when described K channel switching cycle, control described receiving terminal and perform channel switching according to predicted channel switch time dot information, to realize the time synchronized of the channel of described receiving terminal and described service end.

In one embodiment of the invention, based on channel switch time synchronized algorithm, according to the cycle that described channel switches, described channel switch delay temporal information, the received channel switch time dot information of described service end and the channel switch time dot information of accessed described receiving terminal predict the channel switch time dot information of described receiving terminal at K channel switching cycle, comprise: based on least-squares algorithm, linear gradient α between described receiving terminal and described service end and intercept β is calculated according to the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal, the cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict the channel switch time dot information of described receiving terminal at K channel switching cycle at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information.

In one embodiment of the invention, by linear gradient α described in following formulae discovery,

$\mathrm{\α}=({\Σ}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\Σ}_{i=1}^N{{\mathrm{Ts}}_i}^2-N*\stackrel{\‾}{T}{s}^2)$

Wherein, Ts _ifor described service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor described receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, by intercept β described in following formulae discovery,

$\mathrm{\β}=\stackrel{\‾}{T}r-\mathrm{\α}\stackrel{\‾}{T}s$

Wherein, at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information, the cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict that described receiving terminal at the formula of the channel switch time dot information of K channel switching cycle is:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd

Wherein, T is the cycle that described letter is cut, Tr _(K)for described receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for described service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor described channel switch delay temporal information.

In one embodiment of the invention, the cycle that described channel switches is 100ms, and described service end and described receiving terminal are in the network of workshop.

For achieving the above object, the present invention on the other hand embodiment proposes the device of a kind of predicted channel switching time, comprise: receiver module, frame and bulletin frame of N number of time are announced in the service sent for receiving service end, wherein, message request is comprised in described service bulletin frame, channel switch delay temporal information and the described service end channel switch time dot information at i-th channel switching cycle is comprised in i-th time bulletin frame, wherein, N is positive integer, and the time that cycle of being switched by channel of N and transmission described service bulletin frame consume determine, wherein, 1≤i≤N, acquisition module, for after receiving user and confirming the confirmation instruction of described message request, obtains the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, prediction module, the channel switch time dot information of described receiving terminal at K channel switching cycle is predicted for the channel switch time dot information of the cycle switched according to described channel, described channel switch delay temporal information, received described service end and the channel switch time dot information of accessed described receiving terminal, wherein, K is greater than N.

According to the device of predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received by receiver module, then by acquisition module after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, the cycle that last prediction module switches according to channel, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Therefore, this device can accurate predicted channel switching time, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

The device of above-mentioned predicted channel switching time can also have following additional technical characteristic:

In one embodiment of the invention, described prediction module, also for: when described K channel switching cycle, control described receiving terminal and perform channel according to predicted channel switch time dot information and switch, to realize the time synchronized of the channel of described receiving terminal and described service end.

In one embodiment of the invention, based on channel switch time synchronized algorithm, described prediction module, also for: based on least-squares algorithm, calculate linear gradient α between described receiving terminal and described service end and intercept β according to the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal; The cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict the channel switch time dot information of described receiving terminal at K channel switching cycle at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information.

In one embodiment of the invention, by linear gradient α described in following formulae discovery,

$\mathrm{\α}=({\Σ}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\Σ}_{i=1}^N{{\mathrm{Ts}}_i}^2-N*\stackrel{\‾}{T}{s}^2)$

Wherein, Ts _ifor described service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor described receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, by intercept β described in following formulae discovery,

$\mathrm{\β}=\stackrel{\‾}{T}r-\mathrm{\α}\stackrel{\‾}{T}s$

Wherein, at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information, the cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict that described receiving terminal at the formula of the channel switch time dot information of K channel switching cycle is:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd

Wherein, T is the cycle that described letter is cut, Tr _(K)for described receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for described service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor described channel switch delay temporal information.

In one embodiment of the invention, the cycle that described channel switches is 100ms, and described service end and described receiving terminal are in the network of workshop.

The advantage of the aspect that the present invention adds will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.

Accompanying drawing explanation

Fig. 1 is the flow chart of the method for predicted channel switching time according to an embodiment of the invention.

Fig. 2 is the schematic diagram that general channel switches.

Fig. 3 is the schematic diagram that the channel after improving switches.

Fig. 4 predicts the refinement flow chart of receiving terminal at the channel switch time dot information of K channel switching cycle according to an embodiment of the invention.

Fig. 5 is the flow chart of the method for predicted channel switching time according to the present invention's specific embodiment.

Fig. 6 is the overall flow figure of the method for predicted channel switching time according to the embodiment of the present invention.

Fig. 7 is the block diagram of the device of predicted channel switching time according to an embodiment of the invention.

Embodiment

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.

Method and the device of the predicted channel switching time proposed according to the embodiment of the present invention are described with reference to the accompanying drawings.

Fig. 1 is the flow chart of the method for predicted channel switching time according to an embodiment of the invention.

As shown in Figure 1, the method for this predicted channel switching time comprises the following steps:

S1, receives service bulletin frame and the bulletin frame of N number of time of service end transmission.

Wherein, message request is comprised in service bulletin frame, channel switch delay temporal information and the service end channel switch time dot information at i-th channel switching cycle is comprised in i-th time bulletin frame, wherein, N is positive integer, and the time that cycle of being switched by channel of N and transmission service bulletin frame consume determine, wherein, 1≤i≤N.

In one embodiment of the invention, the cycle that above-mentioned channel switches is 100ms, and service end and receiving terminal are in the network of workshop.

Wherein, above-mentioned service end can be roadside unit, and above-mentioned receiving terminal can be vehicle.

Wherein, it is to be appreciated that above-mentioned roadside unit can be used for peritropous vehicle and set up service channel, and interactive service data, and above-mentioned roadside unit can be the root node of the time synchronized in the network of workshop.Wherein, above-mentioned roadside unit can be multiple.

Such as, when the vehicle in normal traveling enters in the scope of workshop network, the service bulletin frame that vehicle receiver roadside unit (service end) sends and time bulletin frame, usually in the network of workshop, due to the interaction flow more complicated of service bulletin frame, need repeatedly to shake hands and just can complete, expend time in basic more than 1 second, within the time in 1 second, the channel switching cycle due to workshop network is 100ms, therefore, this vehicle can receive 8-10 time bulletin frame.

Wherein, it is to be appreciated that said message request can be the information of inviting vehicle to add service in this embodiment, wherein, this service can comprise vehicle early warning distance reminding service, traffic behavior reminding service device and transport condition reminding service etc.

S2, after receiving user and confirming the confirmation instruction of message request, obtains the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively.

Particularly, when receiving terminal receives after user confirms the confirmation instruction of message request, the channel switch time dot information of receiving terminal at i-th channel switching cycle is obtained respectively.

Such as, after user confirms the confirmation instruction of message request, vehicle (receiving terminal) will obtain vehicle (receiving terminal) the 1st respectively to the channel switch time dot information of N number of channel switching cycle.

Wherein, it will be appreciated that, when vehicle (receiving terminal) receives 1 time bulletin frame that roadside unit (service end) sends, obtain the channel switch time dot information of vehicle (receiving terminal) at the 1st channel switching cycle; When vehicle (receiving terminal) receives 2 times bulletin frames that roadside unit (service end) sends, obtain the channel switch time dot information of vehicle (receiving terminal) at the 2nd channel switching cycle; The like, until get the channel switch time dot information of vehicle (receiving terminal) at i-th channel switching cycle.

S3, the channel switch time dot information prediction receiving terminal of the cycle switched according to channel, channel switch delay temporal information, the channel switch time dot information of received service end and accessed receiving terminal is at the channel switch time dot information of K channel switching cycle, wherein, K is greater than N.

Particularly, service end is by the channel switch time dot information of the receiving terminal of acquisition at i-th channel switching cycle, be sent to receiving terminal, then receiving terminal switch according to channel cycle, channel switch delay temporal information, the channel switch time dot information of received service end and accessed receiving terminal channel switch time dot information prediction receiving terminal at the channel switch time dot information of K channel switching cycle, wherein, K is greater than N.

In one embodiment of the invention, as shown in Figures 2 and 3, the time synchronized bulletin frame sequence that the channel adding the broadcast of roadbed side in the flow process that general channel switches switches, receiving terminal is receiving these frames to rear, calculate that (such as based on the linear regression prediction channel switch time algorithm of least square method) goes out the channel switch time dot information at K channel switching cycle by channel switch time synchronized algorithm, then carry out the channel switching of vehicle node in the K moment in cycle.

Wherein, need yes to understand, in this embodiment, the broadcast of said roadbed side can be that roadside unit (service end) is periodically broadcasted.

Wherein, need yes to understand, receiving terminal only in the communication range of service end just can receive service bulletin frame and the time bulletin frame of service end transmission, and service end is based on the above-mentioned service bulletin frame of single-hop broadcast transmission and time bulletin frame, therefore, in the process of predicted channel switching time, can not consider by the interrupt processing delay of each node and wireless transmission delay, thus can reduce the uncertainty of delay.

In an embodiment of the present invention, bunch head of above-mentioned FTSP algorithm can be set as roadside unit (service end).

In one embodiment of the invention, as shown in Figure 4, based on channel switch time synchronized algorithm, the channel switch time dot information prediction receiving terminal of the cycle switched according to channel, channel switch delay temporal information, the channel switch time dot information of received service end and accessed receiving terminal can comprise in the detailed process of the channel switch time dot information of K channel switching cycle:

S31, based on least-squares algorithm, according to the channel switch time dot information of received service end and the linear gradient α between the channel switch time dot information calculating receiving terminal of accessed receiving terminal and service end and intercept β.

S32, the cycle switched according to linear gradient α, intercept β, channel, service end are at the channel switch time dot information of N number of channel switching cycle and the channel switch delay temporal information prediction receiving terminal channel switch time dot information at K channel switching cycle.

Wherein, in one embodiment of the invention, linear gradient α is calculated by following formula (1),

$\mathrm{\α}=({\Σ}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\Σ}_{i=1}^N{{\mathrm{Ts}}_i}^2-N*\stackrel{\‾}{T}{s}^2)---\left(1\right)$

Wherein, Ts _ifor service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, calculate intercept β by following formula (2),

$\mathrm{\β}=\stackrel{\‾}{T}s-\mathrm{\α}\stackrel{\‾}{T}s---\left(2\right)$

Wherein, the cycle switched according to linear gradient α, intercept β, channel, service end at the channel switch time dot information of N number of channel switching cycle and channel switch delay temporal information prediction receiving terminal at the formula (3) of the channel switch time dot information of K channel switching cycle are:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd(3)

Wherein, T is the cycle that letter is cut, Tr _(K)for receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor channel switch delay temporal information.

Further, in one embodiment of the invention, as shown in Figure 5, predict that receiving terminal is after the channel switch time dot information of K channel switching cycle at the channel switch time dot information of the cycle switched according to channel, channel switch delay temporal information, received service end and the channel switch time dot information of accessed receiving terminal, the method can also comprise:

S4, when K channel switching cycle, controls receiving terminal and performs channel switching, to realize the time synchronized of the channel of receiving terminal and service end according to predicted channel switch time dot information.

Such as, when vehicle (receiving terminal) obtains at K channel switching cycle, control vehicle (receiving terminal) and perform channel switching, to realize the time synchronized of the channel of vehicle (receiving terminal) and roadside unit (service end) according to predicted channel switch time dot information.

According to the method for predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received, then after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, finally according to the cycle that channel switches, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Thus, the accurately predicted channel switching time of receiving terminal, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

Usual whole workshop network is made up of multiple workshops sub-network, each workshop sub-network has a cluster head (service end), monitoring vehicle sail cluster head into can after communication range, this vehicle can receive service bulletin frame and the time bulletin frame of cluster head broadcast simultaneously, due to the interaction flow more complicated of service bulletin frame, need repeatedly to shake hands and just can complete, expend time in basic more than 1 second, within the time in 1 second, channel switching cycle due to workshop network is 100ms, therefore, this vehicle can receive 8-10 time bulletin frame, again because the clock drift of each vehicle is certain, so, the channel switch time of vehicle and the channel switch time deviation of cluster head are linear, the channel switch time of vehicle is predicted by the linear regression of least square method.

Be introduced the process of predicted channel switching time below in conjunction with Fig. 6, as shown in Figure 6, the overall flow of the method for this predicted channel switching time comprises the following steps:

S101, determines the cluster head of sub-network.

S102, sub-network cluster head collection period gathers time point when channel switches.

S103, the time point that channel is switched and channel switch delay group angle of incidence bulletin frame.

S104, periodic airtime bulletin frame.

S105, periodically receives the time bulletin frame of ISP and preserves.

S106, judges whether to need to carry out channel switching with cluster head alternately, if so, then performs step S107, if not, then returns step S105.

S107, the linear regression algorithm based on least square method estimates switching channels time deviation at lower a moment.

S108, the channel switch delay channel adding this node switches.

S109, performs channel switchover operation and receives service data.

Wherein, above-mentioned sub-network is the sub-network of workshop network, i.e. workshop sub-network.

According to the method for predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received, then after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, finally according to the cycle that channel switches, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Therefore, the method can accurate predicted channel switching time, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

In order to realize above-described embodiment, the present invention also proposes the device of a kind of predicted channel switching time.

Fig. 7 is the block diagram of the device of predicted channel switching time according to an embodiment of the invention.

As shown in Figure 7, the device of this predicted channel switching time comprises receiver module 100, acquisition module 200 and prediction module 300.

Particularly, receiver module 100 is for receiving service bulletin frame and the bulletin frame of N number of time of service end transmission, wherein, comprise message request in service bulletin frame, comprise channel switch delay temporal information and the service end channel switch time dot information at i-th channel switching cycle in i-th time bulletin frame, wherein, N is positive integer, and the time that cycle of being switched by channel of N and transmission service bulletin frame consume determine, wherein, 1≤i≤N.

In one embodiment of the invention, the cycle that above-mentioned channel switches is 100ms, and service end and receiving terminal are in the network of workshop.

Wherein, above-mentioned service end can be roadside unit, and above-mentioned receiving terminal can be vehicle.

Wherein, it is to be appreciated that above-mentioned roadside unit can be used for peritropous vehicle and set up service channel, and interactive service data, and above-mentioned roadside unit can be the root node of the time synchronized in the network of workshop.Wherein, above-mentioned roadside unit can be multiple.

Such as, when the vehicle in normal traveling enters in the scope of workshop network, vehicle receives by receiver module 100 the service bulletin frame and time bulletin frame that roadside unit (service end) sends, usually in the network of workshop, due to the interaction flow more complicated of service bulletin frame, need repeatedly to shake hands and just can complete, expend time in basic more than 1 second, within the time in 1 second, channel switching cycle due to workshop network is 100ms, therefore, this vehicle can receive 8-10 time bulletin frame.

Wherein, it is to be appreciated that said message request can be the information of inviting vehicle to add service in this embodiment, wherein, this service can comprise vehicle early warning distance reminding service, traffic behavior reminding service device and transport condition reminding service etc.

Acquisition module 200, for after receiving user and confirming the confirmation instruction of message request, obtains the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively.

Particularly, when receiving terminal receives after user confirms the confirmation instruction of message request, acquisition module 200 obtains the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively.

Such as, after user confirms the confirmation instruction of message request, acquisition module 200 will, obtain vehicle (receiving terminal) respectively the 1st to the channel switch time dot information of N number of channel switching cycle.

Wherein, it will be appreciated that, when vehicle (receiving terminal) receives 1 time bulletin frame that roadside unit (service end) sends, acquisition module 200 obtains the channel switch time dot information of vehicle (receiving terminal) at the 1st channel switching cycle; When vehicle (receiving terminal) receives 2 times bulletin frames that roadside unit (service end) sends, acquisition module 200 obtains the channel switch time dot information of vehicle (receiving terminal) at the 2nd channel switching cycle; The like, until acquisition module 200 gets the channel switch time dot information of vehicle (receiving terminal) at i-th channel switching cycle.

Prediction module 300 for switch according to channel cycle, channel switch delay temporal information, the channel switch time dot information of received service end and accessed receiving terminal channel switch time dot information prediction receiving terminal at the channel switch time dot information of K channel switching cycle, wherein, K is greater than N.

In an embodiment of the present invention, as shown in Figures 2 and 3, the time synchronized bulletin frame sequence that the channel adding the broadcast of roadbed side in the flow process that general channel switches switches, receiving terminal is receiving these frames to rear, calculate that (such as based on the linear regression prediction channel switch time algorithm of least square method) goes out the channel switch time dot information at K channel switching cycle by channel switch time synchronized algorithm, then carry out the channel switching of vehicle node in the K moment in cycle.

Wherein, need yes to understand, in this embodiment, the broadcast of said roadbed side can be that roadside unit (service end) is periodically broadcasted.

Wherein, need yes to understand, receiving terminal only in the communication range of service end just can receive service bulletin frame and the time bulletin frame of service end transmission, and service end is based on the above-mentioned service bulletin frame of single-hop broadcast transmission and time bulletin frame, therefore, in the process of predicted channel switching time, can not consider by the interrupt processing delay of each node and wireless transmission delay, thus can reduce the uncertainty of delay.

In an embodiment of the present invention, bunch head of above-mentioned FTSP algorithm can be set as roadside unit (service end).

In one embodiment of the invention, based on channel switch time synchronized algorithm, prediction module 300, also for based on least-squares algorithm, according to the channel switch time dot information of received service end and the linear gradient α between the channel switch time dot information calculating receiving terminal of accessed receiving terminal and service end and intercept β; The cycle switched according to linear gradient α, intercept β, channel, service end are at the channel switch time dot information of N number of channel switching cycle and the channel switch delay temporal information prediction receiving terminal channel switch time dot information at K channel switching cycle.

Wherein, in one embodiment of the invention, linear gradient α is calculated by following formula (1),

$\mathrm{\α}=({\Σ}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\Σ}_{i=1}^N{{\mathrm{Ts}}_i}^2-N*\stackrel{\‾}{T}{s}^2)---\left(1\right)$

Wherein, Ts _ifor service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, calculate intercept β by following formula (2),

$\mathrm{\β}=\stackrel{\‾}{T}r-\mathrm{\α}\stackrel{\‾}{T}s---\left(2\right)$

Wherein, the cycle switched according to linear gradient α, intercept β, channel, service end at the channel switch time dot information of N number of channel switching cycle and channel switch delay temporal information prediction receiving terminal at the formula (3) of the channel switch time dot information of K channel switching cycle are:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd(3)

Wherein, T is the cycle that letter is cut, Tr _(K)for receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor channel switch delay temporal information.

Further, in an embodiment of the present invention, prediction module 300, also for when K channel switching cycle, controls receiving terminal and performs channel according to predicted channel switch time dot information and switch, to realize the time synchronized of the channel of receiving terminal and service end.

Such as, when vehicle (receiving terminal) obtains at K channel switching cycle, prediction module 300 controls vehicle (receiving terminal) and performs channel switching, to realize the time synchronized of the channel of vehicle (receiving terminal) and roadside unit (service end) according to predicted channel switch time dot information.

According to the device of predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received by receiver module, then by acquisition module after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, the cycle that last prediction module switches according to channel, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Thus, the accurately predicted channel switching time of receiving terminal, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

Usual whole workshop network is made up of multiple workshops sub-network, each workshop sub-network has a cluster head (service end), monitoring vehicle sail cluster head into can after communication range, this vehicle can receive service bulletin frame and the time bulletin frame of cluster head broadcast simultaneously, due to the interaction flow more complicated of service bulletin frame, need repeatedly to shake hands and just can complete, expend time in basic more than 1 second, within the time in 1 second, channel switching cycle due to workshop network is 100ms, therefore, this vehicle can receive 8-10 time bulletin frame, again because the clock drift of each vehicle is certain, so, the channel switch time of vehicle and the channel switch time deviation of cluster head are linear, the channel switch time of vehicle is predicted by the linear regression of least square method.

It should be noted that, the explanation of the aforementioned embodiment of the method to predicted channel switching time illustrates the device of the predicted channel switching time being also applicable to this embodiment, repeats no more herein.

According to the device of predicted channel switching time of the embodiment of the present invention, first service bulletin frame and the bulletin frame of N number of time of service end transmission is received by receiver module, then by acquisition module after receiving user and confirming the confirmation instruction of message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively, the cycle that last prediction module switches according to channel, channel switch delay temporal information, the channel switch time dot information of received service end and the channel switch time dot information of accessed receiving terminal predict the channel switch time dot information of receiving terminal at K channel switching cycle.Therefore, this device can accurate predicted channel switching time, thus when ensure that the channel switching between service end with receiving terminal, switching time is consistent, effectively reduces the resource consumption of network and the uncertainty caused by delay, improves the communication efficiency of transfer of data.

In describing the invention, it is to be appreciated that term " first ", " second " only for describing object, and can not be interpreted as instruction or hint relative importance or the implicit quantity indicating indicated technical characteristic.Thus, be limited with " first ", the feature of " second " can express or impliedly comprise at least one this feature.In describing the invention, the implication of " multiple " is at least two, such as two, three etc., unless otherwise expressly limited specifically.

In the description of this specification, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, to the schematic representation of above-mentioned term not must for be identical embodiment or example.And the specific features of description, structure, material or feature can combine in one or more embodiment in office or example in an appropriate manner.In addition, when not conflicting, the feature of the different embodiment described in this specification or example and different embodiment or example can carry out combining and combining by those skilled in the art.

Describe and can be understood in flow chart or in this any process otherwise described or method, represent and comprise one or more for realizing the module of the code of the executable instruction of the step of specific logical function or process, fragment or part, and the scope of the preferred embodiment of the present invention comprises other realization, wherein can not according to order that is shown or that discuss, comprise according to involved function by the mode while of basic or by contrary order, carry out n-back test, this should understand by embodiments of the invention person of ordinary skill in the field.

In flow charts represent or in this logic otherwise described and/or step, such as, the sequencing list of the executable instruction for realizing logic function can be considered to, may be embodied in any computer-readable medium, for instruction execution system, device or equipment (as computer based system, comprise the system of processor or other can from instruction execution system, device or equipment instruction fetch and perform the system of instruction) use, or to use in conjunction with these instruction execution systems, device or equipment.With regard to this specification, " computer-readable medium " can be anyly can to comprise, store, communicate, propagate or transmission procedure for instruction execution system, device or equipment or the device that uses in conjunction with these instruction execution systems, device or equipment.The example more specifically (non-exhaustive list) of computer-readable medium comprises following: the electrical connection section (electronic installation) with one or more wiring, portable computer diskette box (magnetic device), random access memory (RAM), read-only memory (ROM), erasablely edit read-only memory (EPROM or flash memory), fiber device, and portable optic disk read-only memory (CDROM).In addition, computer-readable medium can be even paper or other suitable media that can print described program thereon, because can such as by carrying out optical scanner to paper or other media, then carry out editing, decipher or carry out process with other suitable methods if desired and electronically obtain described program, be then stored in computer storage.

Should be appreciated that each several part of the present invention can realize with hardware, software, firmware or their combination.In the above-described embodiment, multiple step or method can with to store in memory and the software performed by suitable instruction execution system or firmware realize.Such as, if realized with hardware, the same in another embodiment, can realize by any one in following technology well known in the art or their combination: the discrete logic with the logic gates for realizing logic function to data-signal, there is the application-specific integrated circuit (ASIC) of suitable combinational logic gate circuit, programmable gate array (PGA), field programmable gate array (FPGA) etc.

Those skilled in the art are appreciated that realizing all or part of step that above-described embodiment method carries is that the hardware that can carry out instruction relevant by program completes, described program can be stored in a kind of computer-readable recording medium, this program perform time, step comprising embodiment of the method one or a combination set of.

In addition, each functional unit in each embodiment of the present invention can be integrated in a processing module, also can be that the independent physics of unit exists, also can be integrated in a module by two or more unit.Above-mentioned integrated module both can adopt the form of hardware to realize, and the form of software function module also can be adopted to realize.If described integrated module using the form of software function module realize and as independently production marketing or use time, also can be stored in a computer read/write memory medium.

The above-mentioned storage medium mentioned can be read-only memory, disk or CD etc.Although illustrate and describe embodiments of the invention above, be understandable that, above-described embodiment is exemplary, can not be interpreted as limitation of the present invention, and those of ordinary skill in the art can change above-described embodiment within the scope of the invention, revises, replace and modification.

Claims (10)

1. the method for predicted channel switching time, is characterized in that, comprise the following steps:

Receive service bulletin frame and the bulletin frame of N number of time of service end transmission, wherein, message request is comprised in described service bulletin frame, channel switch delay temporal information and the described service end channel switch time dot information at i-th channel switching cycle is comprised in i-th time bulletin frame, wherein, N is positive integer, and the cycle that N is switched by channel was determined with the time that transmission described service bulletin frame consumes, wherein, 1≤i≤N;

After receiving user and confirming the confirmation instruction of described message request, obtain the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively;

The cycle switched according to described channel, described channel switch delay temporal information, the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal predict the channel switch time dot information of described receiving terminal at K channel switching cycle, wherein, K is greater than N.

2. the method for as claimed in claim 1 predicted channel switching time, it is characterized in that, the cycle switched according to described channel described, described channel switch delay temporal information, the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal predict that described receiving terminal is after the channel switch time dot information of K channel switching cycle, also comprises:

When described K channel switching cycle, control described receiving terminal and perform channel switching, to realize the time synchronized of the channel of described receiving terminal and described service end according to predicted channel switch time dot information.

3. the method for as claimed in claim 1 predicted channel switching time, it is characterized in that, based on channel switch time synchronized algorithm, the cycle switched according to described channel, described channel switch delay temporal information, the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal predict the channel switch time dot information of described receiving terminal at K channel switching cycle, comprising:

Based on least-squares algorithm, calculate linear gradient α between described receiving terminal and described service end and intercept β according to the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal;

The cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict the channel switch time dot information of described receiving terminal at K channel switching cycle at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information.

4. the method for as claimed in claim 3 predicted channel switching time, is characterized in that, by linear gradient α described in following formulae discovery,

$\mathrm{\α}=({\mathrm{\Σ}}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\mathrm{\Σ}}_{i=1}^N{\mathrm{Ts}}_i^2-N*\stackrel{\‾}{T}{s}^2)$

Wherein, Ts _ifor described service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor described receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, by intercept β described in following formulae discovery,

$\mathrm{\β}=\stackrel{\‾}{T}r-\mathrm{\α}\stackrel{\‾}{T}s$

Wherein, at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information, the cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict that described receiving terminal at the formula of the channel switch time dot information of K channel switching cycle is:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd

Wherein, T is the cycle that described letter is cut, Tr _(K)for described receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for described service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor described channel switch delay temporal information.

5. the method for the predicted channel switching time as described in any one of claim 1-4, is characterized in that, the cycle that described channel switches is 100ms, and described service end and described receiving terminal are in the network of workshop.

6. the device of predicted channel switching time, is characterized in that, comprising:

Receiver module, frame and bulletin frame of N number of time are announced in the service sent for receiving service end, wherein, comprise message request in described service bulletin frame, comprise channel switch delay temporal information and the described service end channel switch time dot information at i-th channel switching cycle in i-th time bulletin frame, wherein, N is positive integer, and the time that cycle of being switched by channel of N and transmission described service bulletin frame consume determine, wherein, 1≤i≤N;

Acquisition module, for after receiving user and confirming the confirmation instruction of described message request, obtains the channel switch time dot information of receiving terminal at i-th channel switching cycle respectively;

Prediction module, the channel switch time dot information of described receiving terminal at K channel switching cycle is predicted for the channel switch time dot information of the cycle switched according to described channel, described channel switch delay temporal information, received described service end and the channel switch time dot information of accessed described receiving terminal, wherein, K is greater than N.

7. the device of as claimed in claim 6 predicted channel switching time, is characterized in that, described prediction module, also for:

When described K channel switching cycle, control described receiving terminal and perform channel switching, to realize the time synchronized of the channel of described receiving terminal and described service end according to predicted channel switch time dot information.

8. the device of as claimed in claim 6 predicted channel switching time, is characterized in that, based on channel switch time synchronized algorithm, described prediction module, also for:

Based on least-squares algorithm, calculate linear gradient α between described receiving terminal and described service end and intercept β according to the channel switch time dot information of received described service end and the channel switch time dot information of accessed described receiving terminal;

The cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict the channel switch time dot information of described receiving terminal at K channel switching cycle at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information.

9. the device of as claimed in claim 8 predicted channel switching time, is characterized in that, by linear gradient α described in following formulae discovery,

$\mathrm{\α}=({\mathrm{\Σ}}_{i=1}^N{\mathrm{Ts}}_i*{\mathrm{Tr}}_i-N*\stackrel{\‾}{T}s\stackrel{\‾}{T}r)/({\mathrm{\Σ}}_{i=1}^N{{\mathrm{Ts}}_i}^2-N*\stackrel{\‾}{T}{s}^2)$

Wherein, Ts _ifor described service end is at the channel switch time dot information of i-th channel switching cycle, Tr _ifor described receiving terminal is at the channel switch time dot information of i-th channel switching cycle, for Ts _iarithmetic mean, for Tr _iarithmetic mean,

Wherein, by intercept β described in following formulae discovery,

$\mathrm{\β}=\stackrel{\‾}{T}r-\mathrm{\α}\stackrel{\‾}{T}s$

Wherein, at the channel switch time dot information of N number of channel switching cycle and described channel switch delay temporal information, the cycle switched according to described linear gradient α, described intercept β, described channel, described service end predict that described receiving terminal at the formula of the channel switch time dot information of K channel switching cycle is:

Tr _(K)＝α(Ts _(N)+(K-N)*100)+β+T _sd

Wherein, T is the cycle that described letter is cut, Tr _(K)for described receiving terminal is at the channel switch time dot information of K channel switching cycle, Tr _(K)for described service end is at the channel switch time dot information of N number of channel switching cycle, T _sdfor described channel switch delay temporal information.

10. the device of the predicted channel switching time as described in any one of claim 6-9, is characterized in that, the cycle that described channel switches is 100ms, and described service end and described receiving terminal are in the network of workshop.